Hybrid-matrix composites: Materials and manufacturing

One disadvantage of composite materials is their low tolerance to impact and damage as well as low damping properties due to typical brittle matrix materials such as epoxy. In previous studies, non-reinforced rubber-elastic films were locally inserted into composites to improve these material characteristics [1]. The objective of this work is the introduction to hybrid-matrix-composites (HMC), the development of associated production processes and the fabrication of samples in an applied approach. An HMC is characterized by continuous fiber reinforcement in a matrix consisting of elastic and stiff layers. In a first step, different elastomer materials are evaluated with respect to their processability in composite manufacturing processes and their compatibility to established matrix materials such as Epoxy or PA6. Especially thermoplastic elastomer types based on styrene block copolymers (TPE-s), thermoplastic polyurethanes (TPU), two-component silicones as well as ethylene propylene diene monomer rubber (EPDM) show suitable characteristics. For the evaluation of processability, the time and temperature-dependent viscosity of these materials is investigated in rheological experiments since viscosity represents a key parameter for a sufficient impregnation of the fiber bed. Impregnation and consolidation processes in a hot-press and in an autoclave as well as vacuum-infusion processes are investigated, used and adapted for the manufacturing of rubber-elastic reinforced specimens. Optimized parameters for producing HMCs of high and constant quality are presented.